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摘要
The Dabalang pluton, located in Huanan uplift area of the central Jiamusi block, is lithologically medium-to-fine-grained biotite granodiorites, which intrude into Late Permian muscovite monzogranites. LA-ICP-MS zircon U-Pb age is (234±1) Ma, the biotite granodiorites are in early Late Triassic. The Dabalang pluton has high SiO2 content (62. 04%-64. 30%), Al2O3 content (15. 68%-16. 95%), Sr/Y ratio (23. 38-36. 15) and (La/Yb)N ratio (18. 57-33. 04), containing low MgO content (0. 91%-1. 20%), moderate Mg# value (34. 03-37. 27), as well as low Yb content ((1. 18-1. 52)×10-6 with an average of 1. 30×10-6) and Y content ((15. 43-20. 50)×10-6 with an average of 16. 94×10-6), Na2O/K2O is 0. 77-1. 06 with an average of 0. 94. The above geochemical characteristics are similar to the C-type adakites. Considering the active continental margin arc setting of Permian in the eastern margin of Jiamusi block and the distribution characteristics of Late Triassic peripheral accretionary complexes, it is found that the Dabalang pluton may be a product of partial melting of crust below Jiamusi block, which is continuously shortened and thickened due to the subduction of Paleo-Pacific plate towards the lower part of Jiamusi block in Late Triassic. ? 2023 Journal of Earth Sciences and Environment.
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